This is no simple subject. Few Americans were more controversial than the founder of the Church of Jesus Christ of Latter-day Saints, but Beam avoids either lionizing or demonizing the prophet, taking a historical tone that is both skeptical and fair-minded.

Smith's self-promotional, manipulative and even messianic style of leadership can shock the modern reader, as it once shocked mainstream American Christians. But the author also makes clear that Smith's opponents were driven by their own extreme impulses and that, in essence, a nation that had guaranteed religious liberty allowed the Mormon leader to be murdered for his beliefs.

Those beliefs get a clear and concise examination here, especially the introduction of polygamy and how the church practiced it in secrecy, deliberately misleading some of its own members. The book also explains the "doctrine of eternal progression," based on Smith's assertion that "God was once one of us" and that humans can perfect themselves to reach the status of gods. Such radical views created deep and lasting rifts in Smith's flock.

Beam also does a fine job of depicting the lawlessness common along the Mississippi River, where Smith and his followers established Nauvoo, an Illinois town that was once bigger than another boomtown across the state, a place called Chicago. The Mormons were considered interlopers in the Nauvoo area, but Bean rightly notes that many of the "old settlers" who opposed them had been there for only a few years longer.

While "American Crucifixion" masters its setting and era, the book's greatest contribution is its dramatic account of the events, as acted out by many memorable characters.

There was, of course, Smith — described as "prophet, seer, and revelator, the president of the High Priesthood, candidate for the presidency of the United States, king of the Kingdom of God, commander in chief of the armies of Israel, judge, mayor, architect, recorder of deeds, postmaster, hotel operator, steamboat owner, and husband, many times over."

Anyone who thought that Mitt Romney's father, George, was the first Mormon to run for president will be surprised that Smith was a declared candidate for the White House when he was murdered. In fact, many of his chief advisers were far from Nauvoo at the time because they were campaigning for him in the more established precincts of the United States.

Another stirring character was Smith's first wife, Emma, a strong intellectual helpmate who was unable to reconcile herself to the polygamy of her husband, estimated to have had 33 to 48 wives.

Two newspaper editors also played prominent roles.

One was Thomas Sharp of the Warsaw Signal, who spit fire onto the page in denouncing Mormonism. Sharp whipped up the fury of the "old settlers," describing Smith's religion as "a power in league with the Prince of Darkness, not inferior to the Spanish Inquisition in its capacity for secrecy and intrigue."

The other editor was a Mormon dissident, William Law, who started a newspaper called the Nauvoo Expositor to denounce polygamy and other perceived excesses of Smith's leadership. The prophet was enraged by the first and only edition and incited his followers to burn Law's offices, destroy his $2,000 press and scatter his lead type in the muddy street.

This action bolstered anti-Mormon arguments that Smith was trying to form a nation of his own, and the authorities filed charges against Smith.

It's not so common in American history for people to take up arms because someone else's rights to a free press have been violated. But in this case, a growing group of anti-Mormon settlers — part militia and part mob — used the Expositor incident as an excuse to settle the dispute for good.

Enter Thomas Ford, whose story demonstrates that Illinois governors could be utter embarrassments long before Rod Blagojevich. With all-out war looming between the Mormons and their enemies, Gov. Ford stepped in to make peace.

Smith was persuaded to face the charges in the county seat, Carthage, and Ford vouched for his safety there.

That promise was engraved on the wind. As the governor visited Nauvoo to lecture the Mormons on behaving peacefully, a mob attacked the Carthage jail and fatally shot Smith and his brother Hyrum.

Afterward, Ford explained away his neglect, insisting that "the pledge of security to the Smiths was not given upon my individual responsibility."

At a trial of some of the suspected killers, the prosecution performed incompetently, and all were acquitted. Soon Brigham Young was chosen to lead the Mormons, and he guided them away from Nauvoo, to a new life in Utah.

Beam, who received scholarly cooperation from both Mormon and secular sources, delivers the right mix of quoting from archival material and describing events in his own words. A weak spot is the very beginning of the book, which jumps around in setting and chronology in a way that may stall some readers. Which would be a shame, considering how well written this history is overall.

While the prose is engaging, it does come with a quirk. Some of Beam's words — such as irenic, autarky, ambit, uxorious and intermontane — live outside the vocabulary of many readers. But these words appear with enough context to allow the reader to guess correctly. And if we're not going to learn new words in books like this, where are we going to learn them?

Beam's book is full of lessons but never feels like schoolwork. In fact, "American Crucifixion" paints a brilliant picture of religious experimentation, public intolerance and the making of a martyr.

Mark Jacob, a deputy metro editor at the Tribune, is the co-author with Stephan Benzkofer of "10 Things You Might Not Know About Nearly Everything," a collection of their Tribune columns.